Simulation of Torque Characteristics in Drivelines with Universal Joints

The variations of torque in drivelines with single and double cardan U-joints in a 4-wheel-drive articulated farm machine in motion have been studied by computer simulation. A mass elastic model for an engine, power train and the machine is used for the simulation. The effects of tire slips and traction parameters on torque variation of drive shafts have also been included in the study. The torque in drive train input drive shaft with single U-joints having large angular unequality for 40 deg. articulation and 15 deg. oscillation about center pivot has shown severe fluctuations with reversals. The yoke accelerations are also beyond acceptable values. The power train output shaft does not show much of a torque variation because of lower speed and effective inertias and stiffnesses. The driveline torque variation is reduced when the angular unequality is made smaller. The use of double cardan joints with as high a joint angle as 32.5 deg. is found to have lowered the torque fluctuation and has eliminated the torque reversals in the drive train input shaft. The angular accelerations of yokes have also been drastically reduced. The effects of initial tire slips and coefficients of traction are found to be negligible on the torque characteristics of the drive train input shaft. The effects are larger on the torque variations of the front output shaft. The study has further shown that for the same degree of oscillation as above, a double cardan joint would be needed to reduce the torque fluctuation in the PTO input drive shaft.